Elastomeric articles such as gloves may be manufactured from natural rubber or synthetic equivalents. The common process of manufacture involves dipping a shaped mould into a tank containing the natural rubber latex or synthetic polymer to form an elastomeric film on the mould.
A single dipping process can produce elastomeric films with a high probability of having or developing defects, such as a weak spots or pin holes. This can cause problems for products such as gloves as the weak spots or pin holes may expose the wearer to infection or chemical permeation depending on the application. Theoretically multiple dipping can be performed to avoid or limit the risk of defects such as these, but the elastomeric films produced are generally thicker, which is undesirable for products such as gloves due to the reduced sensitivity to the wearer. Another problem associated with multiple dipping methods is that there can be poor adhesion between the individual layers of elastomeric film, which increases the risk of pin-hole/barrier defects and may reduce the durability of the elastomeric film due to delamination between the individual layers. A further problem can be poor pick-up of the latex composition onto the pre-dipped layer on the mould.
There is a need to develop an improved method for producing multilayer elastomeric film products, such as gloves, which results in the production of products with improved qualities.
It is desirable for the process to be capable of application to a wide range of polymeric compositions for forming elastomeric films. In some instances, it is desirable for the product to be free of chemical irritants, including accelerators in particular. When accelerators are not used, the process needs to be capable of forming elastomeric films and articles which still have the required properties of the desired thickness, good coating of film layers onto underlying layers, minimisation of pin-hole defects, mechanical strength, durability and/or freedom from delamination between individual layers.